I. Field of the Invention
The invention relates to a process for bending pipes which preferably are deformable or bendable when heated, with which process the pipe to be bent is heated, if need be, an inside support is put in, and then the bending operation is carried out.
II. Description of the Prior Art
It is known to bend bendable pipes, preferably of plastic, after heating them, an inside support being inserted into the pipes to avoid their deformation, in particular kinking during the bending operation. To this end, to provide an inside support, the pipe is, for example, filled with sand. This has the disadvantage that the sand often sticks to the pipe that must be bent, and it furthermore does not ensure that the sand supports the pipe evenly over its inside surface. It is also known to pull a coil spring into the inside of the pipe prior to the bending operation so as to support it. Also the coil spring does not ensure a uniform supporting of the pipe to be bent over its inside surface, and, in particular, it entails the risk that as a result of the heating the coil spring is pressed into the soft material of the pipe to be bent, so that in the case of complicated bending operations it may no longer be possible to remove the coil spring. The known measures, in particular, do not permit the carrying out of complicated bending operations in opposite directions, which is possible only with the aid of molds.